Endoscopy is a surgical technique that involves the use of an endoscope, to see images of the body's internal structures through very small incisions.
Endoscopic surgery has been used for decades in a number of different procedures, including gall bladder removal, tubal ligation, and knee surgery, and recently in plastic surgery including both cosmetic and re-constructive procedures.
An endoscope may be a rigid or flexible endoscope which consists of five basic parts: a tubular probe, a small camera head, a camera control unit, a bright light source and a cable set which may include a fiber optic cable. The endoscope is inserted through a small incision; and connected to a viewing screen which magnifies the transmitted images of the body's internal structures.
During surgery, the surgeon is able to view the surgical area by watching the screen while moving the tube of the endoscope through the surgical area.
In a typical surgical procedure using an endoscope, only a few small incisions, each less than one inch long, are needed to insert the endoscope probe and other instruments. For some procedures, such as breast augmentation, only two incisions may be necessary. For others, such as a forehead lift, three or four short incisions may be needed. The tiny eye of the endoscope camera allows a surgeon to view the surgical site.
An advantage of the shorter incisions possible when using an endoscope is reduced damage to the patient's body from the surgery. In particular, the risk of sensory loss from nerve damage is decreased. However, most current endoscopes provide only flat, two-dimensional images which are not always sufficient for the requirements of the surgery. The ability of an endoscope to provide three-dimensional information in its output would extend the field of endoscope use within surgery.
The need for a 3D imaging ability within an endoscope has been addressed in the past A number of solutions that provide stereoscopic images by using two different optical paths are disclosed in U.S. Pat. Nos. 5,944,655 , 5,222,477 , 4,651,201, 5,191,203, 5,122,650 , 5,471,237, JP7163517A, .U.S. Pat. No. 5,673,147, 6,139,490, 5,603,687, WO9960916A2, and JP63244011A.
Another method, represented by U.S. Pat. No. 5,728,044 and U. S. Pat. No. 5,575,754 makes use of an additional sensor that provides location measurements of image points. Patent JP8220448A discloses a stereoscopic adapter for a one-eye endoscope, which uses an optical assembly to divide and deflect the image to two sensors. A further method, disclosed in U.S. Pat. No. 6,009,189 uses image acquisition from different directions using one or more cameras. An attempt to obtain 3D information using two light sources was disclosed in U.S. Pat. No. 4,714,319 in which two light sources are used to give an illusion of a stereoscopic image based upon shadows. JP131622A discloses a method for achieving the illusion of a stereoscopic image by using two light sources, which are turned on alternately.
An additional problem with current endoscopes is the issue of lighting of the subject for imaging. The interior spaces of the body have to be illuminated in order to be imaged and thus the endoscope generally includes an illumination source. Different parts of the field to be illuminated are at different distances from the illumination source and relative reflection ratios depend strongly on relative distances to the illumination source. The relative distances however may be very large in a typical surgical field of view, distances can easily range between 2 and 20 cm giving a distance ratio of 1:10. The corresponding brightness ratio may then be 1:100, causing blinding and making the more distant object all but invisible.
One reference, JP61018915A, suggests solving the problem of uneven lighting by using a liquid-crystal shutter element to reduce the transmitted light. Other citations that discuss general regulation of illumination levels include U.S. Pat. No. 4,967,269, JP4236934A, JP8114755A and JP8024219A.
In general it is desirable to reduce endoscope size and at the same time to improve image quality. Furthermore, it is desirable to produce a disposable endoscope, thus avoiding any need for sterilization, it being appreciated that sterilization of a complex electronic item such as an endoscope being awkward in itself.
Efforts to design new head architecture have mainly concentrated on integration of the sensor, typically a CCD based sensor, with optics at the distal end. Examples of such integration are disclosed in U.S. Pat. Nos. 4,604,992 , 4,491,865 , 4,692,608, JP60258515A, U.S. Pat. Nos. 4,746,203 , 4,720,178 , 5,166,787, 4,803,562 , 5,594,497 and EP434793B1. Reducing the overall dimensions of the distal end of the endoscope are addressed in U.S. Pat. No. 5,376,960 and U S. Pat. No. 4,819,065, and Japanese Patent Applications No. 7318815A and No. 70221A. Integration of the endoscope with other forms of imaging such as ultrasound and Optical Coherence Tomography are disclosed in U.S. Pat. No. 4,869,256, 6,129,672, 6,099,475, 6,039,693, 5,502,2399, 6,134,003 and U S. Pat. No. 6,010,449
Intra-vascular applications are disclosed in certain of the above-mentioned patents, which integrate the endoscope with an ultrasound sensor or other data acquisition devices. Patents that disclose methods for enabling visibility within opaque fluids are U.S. Pat. Nos. 4,576,146, 4,827,907, 5,010,875, 4,934,339, 6,178,346 and U S. Pat. No. 4,998,972.
Sterilization issues of different devices including endoscopes are discussed in WO9732534A1, U.S. Pat. Nos. 5,792,045 and U S. Pat. No.5,498,230. In particular JP3264043A discloses a sleeve that was developed in order to overcome the need to sterilize the endoscope.
The above-mentioned solutions are however incomplete and are difficult to integrate into a single endoscope optimized for all the above issues.